Spotlight: RTU Balancing Act

It’s not uncommon for multiple heating and cooling units to serve the same large space, but how do you know one unit isn’t doing all the work while the other sits on the roof and works on its tan? Even if the thermostats are programmed with the same schedule and temperature targets, they might experience slightly different space temperatures to control to, or one might have a remote sensor in a bad location, and thus they could run very differently, or in the worst possible case, even fight each other (ie: one unit cools, while the other heats).

RTUs out of balance
This report from SiteSage shows how much more the existing RTU was running, before thermostat adjustments were made.

One of our quick serve customers had invested in a second Rooftop Unit (RTU) to serve their back of house area, and assumed that it would help take some of the load off the existing RTU serving the space, keeping the area more comfortable. However, data from SiteSage revealed that the new RTU consistently experienced a different space temperature (it was further away from the cookline) and so having the same temperature target as the existing RTU never caused the new RTU to run. Not only was the new RTU not helping keep the space comfortable, it wasn’t relieving any stress from the existing RTU, so the existing RTU still required frequent maintenance and ran through its useful life faster.

After seeing the dramatic difference in runtime with SiteSage data monitoring, the customer adjusted their SiteSage thermostats until the RTUs ran at roughly equal levels; comfort improved and demand on the existing RTU decreased. The customer also considered moving the thermostats’ remote sensors to a more equal place, and/or adjusting the ductwork, but settled on the cheapest and easiest option first of simply adjusting the SiteSage thermostats remotely.

Cheap and easy: what’s not to like?


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